The contents of Tokugan Hei 9-241007, with a filing date of Sep. 5, 1997 in Japan, is hereby incorporated by reference.
The present invention relates to a generator control device used in a hybrid electrical automobile.
An electrical automobile provided with an electrical generator and an engine for driving an electrical generator is termed a series hybrid electrical vehicle (SHEV). Such a vehicle runs by driving the electrical motor with energy from the battery when the charge of the battery is above a set level. When the charge of the battery is low, the engine is activated and electricity is produced by the electrical generator. The electrical energy drives the electrical motor and at the same time charges the battery. When the battery charge reaches a fixed value, the engine is stopped in order to stop generation of energy.
The amount of energy generated by the generator increases with respect to increases in the output of the engine which drives it.
However in order to decrease emissions of toxic exhaust emissions from the engine of the series hybrid electrical vehicle, a catalyst is provided in the engine exhaust system. As described above, the engine is often stopped even if the automobile is running. As a result the engine will have a low temperature immediately after it is operated. The catalyst will thus be inactive and purification of the exhaust gases will not be efficient.
In this context, JP-A-5-328528 teaches that immediately after engine activation, the engine output is set to twice the required output which increases the flow of exhaust gases. By doing so, the catalyst temperature reaches activation temperature in a short time.
However controlling the engine output to double the required output entails the danger of damaging the battery due to excess charging by the generator.
Furthermore, as the engine speed increases, engine noise will appear to increase when the vehicle is stopped or running at a low speed. This will make the driver uneasy. Further it is not desirable that the total amount of exhaust gases output from the engine is increased to such a degree.
It is an object of the present invention to realize early catalyst activation and provide for the thermal protection of peripheral engine components not only by efficient driving so that the generator generates enough to charge the battery but also by variation of the driving point on the basis of demanded exhaust gas temperature.
In order to achieve this object, the electrical generator control device of the electrical automobile of the present invention is provided with an electrical motor for driving the vehicle, a battery to supply electrical power to the electrical motor, a generator for supplying electrical energy to the electrical motor as well as the battery, an engine to drive the generator, and a controller which controls the output of the engine so that, at least when the charge of the battery is below a set level, the generator is driven and the amount of electrical energy produced meets the required level.
The controller is constituted by a micro-computer and functions on the basis of the following program. The load of the generator is controlled so that an efficient engine rotation speed is achieved at that engine output. The required conditions of the engine exhaust gas temperature are judged. When required conditions of the engine exhaust gas temperature differ from the exhaust gas temperature at the present driving conditions, while maintaining the same engine output, the generator load is varied to change the rotation speed of engine so that an exhaust gas temperature results that corresponds to the required temperature.
The details as well as other features and advantages of the invention are set forth in the remainder of the specification and are shown in the accompanying drawings.